A gas generator used to expand and inflate the airbag rapidly so as to protect a vehicle occupant from the shock at a car collision is built in an airbag module secured in a steering wheel and an instrument panel. Some gas generators are designed for an air-belt and built in an airbag module arranged in a buckle of a seatbelt. The gas generator operates to ignite an igniter device (squib) by an application of electric current thereto to burn gas generant by the flames from the igniter device, thereby generating a large amount of gas rapidly.
In recent years, in order to increase a degree of freedom in design of an interior of an automobile, limitations are imposed on the shape and size of the gas generator and reduction in size of the gas generator is being increasingly demanded.
In general, the gas generator is designed to cool down high temperature gas generated by the burning of the gas generant by letting the gas pass through a filtering member fitted in the gas generator before discharged. However, along with increasing size reduction of the gas generator, the need arises to reduce thickness of the filtering member itself having the effects on the cooling of the high temperature gas, so it becomes increasingly harder for the filtering member to cool down the gas sufficiently before discharged.
In the light of the problem mentioned above, the present invention has been made. It is an object of the present invention to provide a gas generator that can allow the sufficient cooling of high-temperature gas generated by the burning of the gas generant before discharged from the gas generator, to control the temperature of the discharged gas easily, even when the gas generator is reduced in size.